There are 56 bat species in South Africa and they are either insectivorous and eat mosquitoes, moths and beetles so do leave a dead tree in the garden which will attract insects. Fruit eaters and nectar feeders help with pollination and seed dispersal. To encourage and keep bats, keep an environmentally friendly space without the use of insecticides and poisons. Put up a light to attract the insects which will then attract the bats. Make sure that you have tall trees in which they roost. The fruit bats eat big, juicy ripe fruit so plant a few fruit trees and Ficus species for them.